Kinetic Spectrophotometric Determination of Paroxetine Hydrochloride in Formulations and Biological Fluids

Abstract

A simple kinetic spectrophotometry method has been developed for the determination of paroxetine-HCl in bulk powder, dosage forms and biological fluids.The method is based on the oxidative coupling of paroxetine HC1 with 3-methylbenzothiazolinone hydrazone / ferric chloride system in aqueous hydrochloric acid. At a fixed time of 30 min at room temperature, the formed blueish violet product was measured at 591 nm. Concentration of the drug was calculated using the calibration equation for fixed time method where good correlation was obtained in the range of 2-20 ng ml"1 of paroxetine HC1 with a limit of detection of 0.24 jig ml*1 (6.5x10"7 M). The recoveries was 100.1 ±0.74% and RSD was 0.37%. The procedure was successfully applied to commercial tablets with recovery of 97.6±1.07 % and the results obtained were comparable with those given by a reference method. The method could be extended to the in vitro determination of paroxetine HC1 in urine and serum, with recoveries of 101,2± 1.05% and 88.4±2.86%, respectively. The stoichiometry of the reaction was studied using the limiting logarithmic method and the 'proposed reaction pathway is presented.